title: Supported liquid membrane enrichment combined with atomic absorption spectrometry for the determination of lead in urine.
abstract: Supported liquid membrane (SLM) methodology was used for sample clean-up and enrichment of lead in urine prior to determination by AAS. Lead ions at pH 3 were extracted across a membrane solution containing 40% m/m di-2-ethylhexylphosphoric acid dissolved in kerosene and back-extracted into an acceptor solution of 1 mol l-1 nitric acid. The mechanism of mass transfer is a proton gradient across the membrane. The concentration range investigated was between 5 and 80 ng ml-1 and the extraction time was varied between 0.5 and 4 h, leading to enrichment factors of up to 200. The extraction efficiency was about 95%. The detection limit, expressed as 3 sigma of five replicate determinations, using a 45 min enrichment of a urine sample low in lead, was 0.1 and 6.0 micrograms l-1 for ETAAS, and FAAS respectively. The results obtained by the developed method agreed with those obtained by direct ICP-MS determinations for reference urine samples and samples from occupationally lead-exposed workers. The linear correlation coefficient was 0.97, the slope of the regression line was 1.06 and the intercept was -0.37 microgram l-1. The 95% confidence intervals for the slope and the intercept were 0.95 to 1.18 and -3.9 to 3.1, respectively. The results at the 95% confidence level for reference urine material were of 91 +/- 1.5 and 92 +/- 2.0 micrograms l-1 for ICP-MS and SLM-AAS, respectively, which agreed well with the recommended value of 90 micrograms l-1 (range 83-97 micrograms l-1).
authors.affiliation: Department of Analytical Chemistry, University of Lund, Sweden.
authors.forename: N K
authors.initials: NK
authors.lastname: Djane
authors.forename: I A
authors.initials: IA
authors.lastname: Bergdahl
authors.forename: K
authors.initials: K
authors.lastname: Ndung'u
authors.forename: A
authors.initials: A
authors.lastname: Schütz
authors.forename: G
authors.initials: G
authors.lastname: Johansson
authors.forename: L
authors.initials: L
authors.lastname: Mathiasson
mesh_terms: D007854:Lead / Q000652:urine*; D013058:Mass Spectrometry; D008567:Membranes, Artificial; D015203:Reproducibility of Results; D013054:Spectrophotometry, Atomic
chemical_list: D008567:Membranes, Artificial; D007854:Lead